Re: [PATCH v2 1/3] soc: qcom: llcc: Pass SoC specific EDAC register offsets to EDAC driver

From: Sai Prakash Ranjan
Date: Wed Aug 24 2022 - 09:08:14 EST

On 8/24/2022 6:27 PM, Manivannan Sadhasivam wrote:
On Wed, Aug 24, 2022 at 10:43:51AM +0530, Sai Prakash Ranjan wrote:
On 8/23/2022 9:01 PM, Manivannan Sadhasivam wrote:
On Mon, Aug 22, 2022 at 05:29:13PM +0530, Sai Prakash Ranjan wrote:
Hi Mani,

On 8/12/2022 11:36 AM, Manivannan Sadhasivam wrote:
The LLCC EDAC register offsets varies between each SoCs. Until now, the
EDAC driver used the hardcoded register offsets. But this caused crash
on SM8450 SoC where the register offsets has been changed.

So to avoid this crash and also to make it easy to accomodate changes for
new SoCs, let's pass the SoC specific register offsets to the EDAC driver.

Currently, two set of offsets are used. One is SM8450 specific and another
one is common to all SoCs.

Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
<snip> ...

static const struct qcom_llcc_config sm8350_cfg = {
@@ -309,6 +370,7 @@ static const struct qcom_llcc_config sm8350_cfg = {
.size = ARRAY_SIZE(sm8350_data),
.need_llcc_cfg = true,
.reg_offset = llcc_v1_2_reg_offset,
+ .edac_reg = &common_edac_reg,
};
static const struct qcom_llcc_config sm8450_cfg = {
@@ -316,6 +378,7 @@ static const struct qcom_llcc_config sm8450_cfg = {
.size = ARRAY_SIZE(sm8450_data),
.need_llcc_cfg = true,
.reg_offset = llcc_v21_reg_offset,
+ .edac_reg = &sm8450_edac_reg,
};

Can we have LLCC version specific register offsets instead of SoC specific similar to reg_offset callbacks?
For SM8450, it would be llcc_v21_edac_reg and for others llcc_v1_2_edac_reg instead of common_edac_reg.
common_edac_reg is very general and is not exactly common for all, its just common for SoCs with same LLCC.

I thought about it but I was not sure if rest of the SoCs are using version
v1.2. I know that reg_offset uses v1.2 but I was skeptical and hence used the
SoC specific offsets.

Can you confirm if rest of the SoCs are using v1.2?
LLCC versioning follows w.x.y.z format and w and y are major and minor versions based
on which the naming for reg_offsets is chosen.

Now in above reg_offsets, llcc_v1_2 is not v1.2, it means v1.0 or v2.0 where 1, 2 is a major version
and 0 is a minor version. llcc_v21 is actually v2.1 where 2 is a major and 1 is a minor version.
I know the naming is pretty bad, should probably replace llcc_v1_2 with llcc_v1_0_v2_0 and
llcc_v21 with llcc_v2_1? Note here minor version is important because SM8350 is v2.0 and uses
old reg offsets.

Yeah it is confusing. I think we should just use the base LLCC version
that got changed with the previous one and add a comment on top of the
definition. For instance, all of the SoCs before SM8450 should use
llcc_v1_reg_offset since the LLCC version starts from v1.0.0 and SM8450 should
use llcc_v2_1_reg_offset since it supports the LLCC reg offset that got changed
since v2.1.0. Thoughts?

Ya sounds good, only exception is SM8350 which is v2.0 but will be using v1 in naming but I guess its OK.

Thanks,
Sai

Thanks,
Mani

So coming to your query now, all other SoCs except SM8450(which uses v2.1) are using LLCC v1.0
or v2.0, so it is valid to use the same logic as reg_offsets for edac_reg.

Thanks,
Sai

Thanks,
Mani

Version based is more applicable as multiple SoCs might use same LLCC versions and would reduce SoC specific data
which would be needed for every SoC in case some newer LLCC comes out. I know you could just call sm8450_edac_reg
for lets say sm8550 or so on to reduce duplication but that won't look good.


Thanks,
Sai